This goldfish breed is a fat little fish with a brain-like growth on the top of their heads.
This brain-like growth begins to develop when the fish are around the age of 4 months old.
The growth should be fully developed when the Oranda is around the age of 2 years old. Although, some Orandas take a little longer to develop it.
You may also see this brain-like growth referred to as a wen or a hood. The Oranda is not the only goldfish breed to produce this hood.
The Lionhead and the Ranchu develop a hood as well. Their eyes are sometimes hard to find if their hoods grow too large.
The Oranda Goldfish is one of the egg-shaped goldfish breeds.